The present invention relates to apparatus for digging clams, and more particularly to a clam gun for manually excavating clams from subsurface locations along sandy beaches.
Non-commercial clam digging is a popular sport along sandy beaches and other tidal areas where clams can be found. The subsurface location of a particular clam can be identified by the presence of air bubbles. Clam digging with a conventional shovel has proven to be laborious and time consuming.
A number of manual apparatus have been developed for quickly and easily excavating clams. One such apparatus is generally referred to as a clam gun. U.S. Pat. Nos. 2,802,689 and 3,089,721 disclose conventional clam guns. Each has a generally cylindrical sand housing having an upper end wall and an open lower end. The lower end of a vertically extending tube is secured to the upper end wall of the housing. The bore of the tube communicates with the interior of the housing. A horizontally extending handle is provided for forcing the housing into the wet beach sand hopefully about a clam. Thereafter, an outlet aperture at the upper end of the tube is covered with a thumb or finger. When the user begins to withdraw the housing from the beach sand, a partial vacuum is created in the interior of the housing above the sand contained therein. When the housing is completely withdrawn a core of sand and hopefully a clam embedded therein are removed. Thereafter the housing is moved to a convenient discharge location and the outlet aperture is uncovered to release the partial vacuum. The core of sand and the clam embedded therein fall out of the housing and the clam is readily retrieved by hand.
A principle drawback of conventional clam guns has been the amount of force which is required to withdraw the housing from the beach sand. As the user begins to withdraw the housing, a partial vacuum is created in the resulting cavity in the beach sand adjacent the lower end of the housing. This partial vacuum creates a suction effect which impedes withdrawal of the housing. Substantial upward pulling forces have been required to overcome the suction effect. Thus, the use of a conventional clam gun has been a strenuous activity often quickly exhausting the user.
In addition, the suction effect increases in magnitude in proportion to the increase in the cross-sectional area of the clam gun housing. If the suction effect could be eliminated, clam gun housings of significantly larger interior volume could be made. This would increase the likelihood of clam retrieval. Clam guns heretofore known have not included any means for eliminating the suction effect.